The present invention relates generally to systems for detecting the presence and optionally the position of a product within a container or package, and more particularly, to an apparatus and method for verifying the presence in the container of an ophthalmic product such as a contact lens.
Automated systems are used for producing ophthalmic lenses as disclosed in U.S. Pat. No. 5,080,839. These systems have achieved a very high degree of automation and enable lenses to be molded, removed from the molds, further processed and subsequently packaged, all without any direct human involvement. Even with highly automated systems, however, it has been necessary for each package to be checked visually by personnel to verify that the package contained a lens. These arrangements have increased manpower requirements and the associated labor costs. Automated loading of lenses without verifying an actual transfer of a contact lens into a package can result in more than two percent of processed packages being shipped without a lens. This is more than ten times the average rate found on one production line which uses manual loading of lenses.
In one prior art system disclosed in U.S. Pat. No. 5,568,715, detection of a lens in a package is accomplished by backlighting the package with diffuse light and performing an optical inspection with a video camera. In this system, the package is illuminated from the bottom and a camera module disposed over the package takes a picture of the package. The image is processed by a computerized image processing system to determine whether the lens is missing from the package. While this approach works relatively well, it is expensive and software intensive.
U.S. Pat. No. 5,633,504 discloses a system and method for inspecting a hydrated contact lens by illuminating the lens and photographing with a camera the fluorescent light generated in the lens or in some portion of the receptacle and blocked by the lens. In the preferred method, the lens is provided with an ultraviolet absorbing medium. In one embodiment, light having certain wavelengths will induce fluorescence in the lens and cause the lens to appear as a bright area against a dark field. Defects in the lens appear darker than the surrounding areas. In another embodiment, a part of the lens holding receptacle or support is made to fluoresce by exposure to light having wavelengths outside of the range of wavelengths used by the camera. These wavelengths do not cause lens fluorescence such that defects appear as light areas within the lens.
Accordingly, there exists a need for a new type of lens detection system, which provides low cost detection with high accuracy. The detection system may be used as part of an automated detection system which includes a transport and ejector conveyor for ejecting any defective packages which the automated detection system determines are missing lenses in the packages.
It is a primary object of the present invention to provide a system and a method for verifying the presence and optionally the presence and position of an ophthalmic product disposed in the container by directing electromagnetic radiation at the product/container combination.
It is another object of the present invention to provide a system for verifying the presence or absence of an ophthalmic product disposed in the container which provides an accuracy of detection greater than 1 in 100,000.
It is still another object of the present invention to provide a system for verifying the presence or absence of an ophthalmic product disposed in a container which is economical to manufacture and use.
In accordance with the above objects and additional objects that will become apparent hereinafter, the present invention provides a system for determining the presence and optionally the position of an ophthalmic product such as a contact lens in a container. The lens will fluoresce, absorb or reflect, preferably absorb or reflect, most preferably absorb, electromagnetic radiation in a different amount than the container. This difference may be due to a media included in the lens, which reacts differently to electromagnetic energy in a specified wavelength range than does the container. The container includes a receptacle for the lens and preferably is at least partially constructed from a material which is substantially transparent to electromagnetic energy in the specified wavelength range. The detection system includes an apparatus for detecting the presence and optionally the position of an ophthalmic product in a container, comprising:
(a) a source of electromagnetic energy located relative to the container to direct electromagnetic energy at the container;
(b) a detector disposed relative to the container and the source to detect electromagnetic energy from the source which passes through or is reflected by the product and the container; and
(c) a processor for determining the presence or position of the product in the container responsive to absorption, reflection or fluorescence of the electromagnetic energy by the product.
Another embodiment of the apparatus of the present invention for detecting the presence and optionally the position of an ophthalmic product in a container comprises:
(a) a source of electromagnetic energy located relative to the container to direct electromagnetic energy at the container;
(b) a reflective surface located such that the container is disposed between the source and the reflective surface;
(c) a detector disposed relative to the container and the source to detect electromagnetic energy from the source which is reflected by the product, the container and the reflective surface; and
(d) a processor for determining the presence or position of the product in the container responsive to fluorescence, absorption or reflection of the electromagnetic energy by the product.
The present invention also provides a method for detecting the presence or presence and position of an ophthalmic product in a container, the product including a media which absorbs or reflects electromagnetic energy of a frequency in a specified range, the method comprising:
a) directing electromagnetic energy at the product and the container;
b) detecting the electromagnetic energy which passes through or is reflected by the product and the container; and
c) processing the detected electromagnetic energy to determine the presence or position of the product in the container.
The present invention provides a relatively simple and economical system for determining the presence and optionally the position of an ophthalmic product in a container. It does not comprise a vision system, nor complicated software which does pixel-by-pixel analysis of an image, that is, image morphology.